1. Field of the Invention
The present invention relates to a speech-controlled phonetic typewriter or display device using a two-tier approach, and more particularly to a method and apparatus, not speaker-dependent, by means of which a spoken input of connected American English words can be received and utilized to produce, in real time, a simultaneous printed output which is, to the maximum extent possible, in the form of conventionally spelled words.
2. Description of the Prior Art
In recent years, there have been various efforts to convert speech directly into print as it is being spoken. Such efforts have taken advantage of the development of high-speed computers with multiplexed program operations, but such efforts have required programming and availability of extensive computer facilities.
Most recent efforts by the present inventor have been directed to the detection and analysis of speech sounds instantaneously without a computer, the conversion of the sounds by means of comparators, timers, filters and switching circuits into a real-time electrical phonemic analog of that which is being said, and the use of a special-purpose digital computer component to process and match syllabic sequences of sounds in the language. Such a technique and arrangement have been disclosed in U.S. Pat. No. 3,646,576--Griggs, which discloses the use of a computer element reduced in size, which element is used not for phonetic detection, but simply as a means of providing an output which is as closely related as possible to conventional printing, such being obtained by means of a pre-stored vocabulary of 12,000 words.
Other prior art techniques have included that disclosed in the U.S. Pat. No. 3,808,371--Griggs, which discloses real-time mechanical detection of diphthongs for a speech-controlled phonetic typewriter. More specifically, the technique disclosed in the latter patent relates to an improvement by means of which diphthongs may be distinguished from other sounds, including simple, single-vowel sounds. The distinction or identification of diphthongs is obtained by means of transduced electrical signals, each of which represents a distinctive diphthong relevant for subsequent written transcription by machine.
A further prior art technique is disclosed in U.S. Pat. No. 3,846,586--Griggs, which discloses an improved single-oral-input real-time analyzer with written print-out. The improvement involves a first step of automatic and instantaneous conversion of speech into writing by separating the speech into various types of components (such as fricatives, vowels, plosives, nasals, etc.) by the use of only a single oral input. This is distinguished from the original development (disclosed in aforementioned U.S. Pat. No. 3,646,576), wherein two inputs were used, one from the throat and one oral. According to the technique of the aforementioned, U.S. Pat. No. 3,846,586, once the appropriate components of speech are separated, various switches, gates and other circuit mechanisms are used to actuate other circuitry, as well as a typewriter which records the input sounds.
The various techniques of the prior art, as exemplified by the aforementioned techniques, are burdened with various disadvantages. For example, various bandwidths and amplitude ratios cited in the previous patents are insufficiently precise for optimal real-time operation. The syllabic analysis provided in the tables of the above-discussed patents is inadequate and was based upon a premise that the syllables of the written language are in parallel relationship to the sonic building blocks of the spoken language. This proves not to be the case, as implied subsequently in this description.